Specifications

Chapter 16 – Audio Commands
Multi-Tech Systems, Inc. AT Commands for EDGE (E1) Modems (S000474A) 271
16.17 AT^SNFTTY Signal CTM Audio Mode Capability
Description: The Multi-Tech wireless device offers basic support for equipment using the CTM standard
(Cellular Text Telephone Modems).
If CTM mode is activated, the ME will set the necessary bearer capability bit on outgoing (mobile
originated) calls and incoming calls with this bearer capability bit set are accepted.
If CTM mode is disabled, the ME will clear the bearer capability bit on mobile originated calls and
incoming calls with the bearer capability bit set are rejected because the Multi-Tech wireless
modem expects that CTM coded speech data cannot be decoded by the TE.
Designed to set the module’s speech system into CTM mode, the AT^SNFTTY command allows
a CTM device to be connected to one of the three audio interfaces.
Requirements for using CTM features:
• CTM functionality requires audio mode 5 or 6 with all audio parameters set to their factory
default.
To activate CTM mode, first enter the AT^SNFS command to select audio mode 5 or 6, then
use AT^SNFI and AT^SNFO to restore the default values. Alternatively, factory defaults of
all audio parameters in audio modes 2 - 6 can easily be set with AT^SNFD. To deactivate
/CTM mode make sure that either audio mode 5 or 6 is set. Keep in mind that the CTM
mode is non-volatile. The audio mode, however, is volatile (power-up default is audio mode
1) unless stored to the user defined profile with AT^SNFW. Therefore, if restarted while in
CTM mode the ME may need to be reconfigured for audio mode 5 or 6 before the CTM
mode is selectable again after the reboot.
• Depending on which audio interface the CTM device is connected to select the according
settings via AT^SAIC.
Syntax: Test Command: AT^SNFTTY=?
Response: ^SNFTTY: (list of supported <audioState>s)
OK
Read Command: AT^SNFTTY?
Response: ^SNFTTY: <audioState>
OK
ERROR
+CME ERROR: <err>
Write Command: AT^SNFTTY=<audioState>
Response: OK
ERROR
+CME ERROR: <err>
Parameter:
<audioState>
This parameter is non-volatile.
0 Audio path is in normal speech mode.
1 Audio path is in CTM mode (external CTM modem).
2 Audio path is in CTM mode (internal CTM modem).
Notes:
• This command is not PIN protected.
• This command is not supported in airplane mode.